Braking system



March 23, 1937. J LOGAN, JR l 2,074,751

BRAKING SYSTEM Filed July 19, 1935 3 Sheets-Sheet l INVENTOR nu) JOHN w.LQGANQR.

-` HATTORNEY March 23, 1937.

J. W. LOGAN, JR 2,074,751

BRAKING SYSTEM Filed July 19, 1935 3 Sheets-Sheet 2 x Fig 2 ATTORNEYMarch 23, 1937. J, w LOGAN, JR

BRAKlNG SYSTEM Filed July 19, 1935 3 sheets-sheet 3 V VV bill);

INVENToR JOI-IN VV. I OGANJR.

ATTORNEY Patented Mar. 23, 1937 UNITED STATES wim PATENT OFFICE BRAKINGSYSTEM Application July 19, 1935, Serial No. 32,145

30 Claims.

This invention relates to braking systems, and more particularly tobraking systems for traction vehicles and railway trains employing bothan electric brake and a friction brake.

In the braking of high speed trains and vehicles it is desirable thatthe brakes provided be operable to produce high initial r-etardingforces, so that the train or vehicle may be decelerated in a minimumlength of time. Where friction type brakes alone are employed it isdifcult to produce the required high initial retarding forces, becausethe coefficient of friction between the rubbing parts of a frictionbrake is lower at the high speeds than at the low speeds. Therefore, ifa friction brake is applied with a high degree of braking force at highspeeds, then the braking force must be reduced as the speedof thevehicle or train diminish-es, or otherwise wheel sliding may occur.

A desirable type of brake to employ for high speed type trains andVehicles which will produce high initial retarding forces with lessdanger of wheel sliding, is the electrodynamic type, as for example thespecific type commonly referred to as the eddy current brake. Acharacteristic feature of th-e eddy current brake is that it may bedesigned to produce a substantially constant braking effect over a widerange of vehicle speeds. Since the braking effect thus produced issubstantially constant, the rate of retardation for a given load will besubstantially constant. The operator may therefore select a desired rateof retardation by selecting the degree of current supplied to operatethe eddy current brake.

At low rotational speeds, however, the eddy current brake decreases ineffectiveness, the braking eff-ect produced thereby diminishing, rstslowly and then rapidly, until at Zero rotational 'speed the eddycurrent brake produces no braking effect. It is therefore both desirableand necessary that where an eddy curr-ent brake is employed asupplementary form of brake, preferably a friction type brake, beemployed to insure stopping of the vehicle or train, and to hold it atrest.

A principal object of the present invention is to provide an improvedform of braking equipment for high speed trains and vehicles employingboth an electric brake and a friction brake.

Friction brakes for railway vehicles and trains are preferablycontrolled by some form of fluid pressure means. A desirable method ofcontrol is to control the degree of application of the friction brake byvarying the pressure of a fluid in a control pipe. Since a friction typebrake is both desirable and necessary as supplementary to an eddycurrent type brake, it is a further object of this invention toprovide abraking equipment as heretofore referred to in which both the eddycurrent brake and the friction brake are controlled according tovariations of pressure of fluid in a control pipe. A still furtherobject of the invention is to provide a combined electric and fluidpressure brake equipment as just referred to, in which both type brakesare normally conditioned to be operable but with the fluid pressurebrake held unapplied until the electric brake decreases in effectivenessbelow a predetermined or chosen value, and with the fluid pressure brakethen cut into action to a degree below that at which the electric brakewas applied, but sufcient to brake the train or vehicle to a stop.

If in such a brake system as that just referred to, the decrease ineffectiveness of the eddy current brakes is due alone to wheel slipping,the fluid pressure brakes might be applied and thus aggravate thesituation. If, however, the fluid pressure brakes are held unappliedduring the wheel slipping condition the slipping wheels may again pickup speed, because as they reduce in speed the eddy current brakingeffect also reduces in degree, so that the tendency to slip is reduced.Or the eddy current brakes may be wholly released during the slippingperiod. In either case the slipping wheels will in some predeterminedlength of time return to substantially the original or normal speed,depending upon the adhesion between the wheels and rails. Theapplication of the fluid pressure brakes should therefore be de' layedso as to permit this return to normal speed. It is therefore a furtherobject of the invention to delay application of the fluid pressurebrakes for a predetermined interval of time when the eddy current brakesdecrease in effectiveness below the value which would normally cut thefluid pressure brakes into action.

If the train or vehicle is brought to a stop with the eddy currentbrakes fully energized, undue heating and possible burning out of theeddy current brake windings may result. To prevent this, it is a furtherobject of the invention to provide means for deenergizing the eddycurrent brake windings when the vehicle or train comes to a stop.

If the load on the vehicle or train were at all times constant, thedegree of energization of the eddy current brake windings woulddetermine the rate of retardation throughout the greater portion of thedeceleration period. However, as will be Obvious, the load will varyover a wide range,

so that one degree of energization may produce one rate of retardationunder one load condition and a different rate of retardation under adifferent load condition. It is a yet further object of the invention toprovide means for producing substantially the same rate of retardationfor a given degree of energization of the eddy current brake windingsregardless of load conditions.

At times it may be desirable to render the electric brake inoperativeand effect applications by means of the fluid pressure brake only, asfor example when switching about the terminal yards. It is therefore astill further object of the invention to provide means for manuallyrendering the electric brake inoperative at the will of the operator.

A still further object of the invention is to provide a novelarrangement of apparatus for generally carrying out the aforestated andother objects, as will more fully appear from the following description,which is taken in connection with the attached drawings, wherein,

Fig. 1 is a schematic and diagrammatic arrangement of apparatuscomprising one embodiment of the invention adapted to a single vehicle.

Fig. 2 is a diagrammatic view of a brake valve device shown to the upperleft in Fig. 1.

Fig. 3 is a diagrammatic View of a retardation detector device shown atthe extreme left of Fig. 1.

Fig. 4 is a diagrammatic View of a reducing relay valve device showncentrally of Fig. 1.

Fig. 5 is a diagrammatic view of an eddy current brake control deviceshown at the upper right of Fig. 1.

Fig. 6 is a view along the line 6-6 of Fig. 5.

Fig. '1 is a diagrammatic view of a transfer valve device showncentrally of Fig. 1.

Considering now briefly at first the apparatus shown in the drawings,two eddy current brake devices are indicated by the two windings I0 andthe two rotors I I. Each eddy current brake device is assumed to beassociated with a vehicle axle, and for the purpose of simplicity only.v enough brake devices have been shown for two axles, corresponding toa two axle truck.

The friction brake devices are indicated by the brake cylinders I2.These brake cylinders may actuate braking elements of any of thecommonly employed types of brakes, or they may actuate shoes I3 intoengagement with the peripheries of the eddy current brake rotors II, inthe manner disclosed and described in my Patent No. 2,012,747.

For initiating and controlling applications of the brakes manually,there is provided a brake valve device I5, which controls the supply offluid under pressure to and its release from a straight air pipe I6. Thebrake valve device I5 supplies fluid under pressure to the straight airpipe I5 at one end from a main reservoir I1. In order that fluid underpressure may be locally supplied from a local supply reservoir I8 to thestraight air pipe, as on each car in a train, there is provided amagnetvalve device 20 which operates synchronously with the brake valvedevice I5.

For controlling operation of the eddy current brake devices bothaccording to the degree of pressure in straight air pipe I6 andaccording to the load on the vehicle, there is provided an eddy currentbrake control device 22. A line switch 23 controls the circuit throughwhich current is supplied to the eddy current brake devices, while apneumatic switch 24 controls energization of this line switch inresponse to fluid supplied to the straight air pipe.

In order that an application of the fluid pressure brakes shall besuppressed so long as the eddy current brakes are effective, there areprovided a power response relay 25, a suppression magnet valve device26, and a transfer valve device 28.

For the purpose of cutting the fluid pressure brakes into action upondie-away of the eddy current brakes, there are provided a retardationdetector device 30 and a die-away magnet valve device 3l.

For the purpose of limiting the degree of application of the uidpressure brakes to a predetermined fraction of the degree of applicationof the eddy current brakes, there is provided a reducing relay valvedevice 32.

To effect a release of the eddy current brakes and to prevent for apredetermined interval of time application of the fluid pressure brakesassociated with wheels which begin to slip, there are provided checkingwindings 33 associated with the eddy current braking devices, rectifierdevices 34, a wheel slip detector relay 35, and a selector relay 36.

For the purpose of effecting deenergization of the eddy current brakewindings Ill when the vehicle (or train) comes substantially to a stop,

there are provided a motion detector relay 38 and a motion detector 39.

In order that the operator may at will render the eddy current brakesinoperative, there is provided a push switch device 40.

When a braking equipment embodying the invention is adapted to a train,the brake valve device I5, the retardation detector device 30, thepneumatic switch device 24, the motion detector relay 3S, the motiondetector device 39, push switch device 40, and main reservoir I1 need besupplied only on the head end or control car. All other devices andparts are then supplied locally on each car in the train as well as onthe head end car, or in the case of an articulated type train on everyother car.

Considering now in detail the devices and apparatus heretofore brieflyreferred to, the brake valve device I5 is embodied in a casing having apressure chamber 42 which is in constant open communication with thestraight air pipe I6. For controlling the supply of uid under pressureto the pressure chamber 42, there is provided a supply valve 43 urgedtoward a seated position by a spring 44.

For controlling the release of fluid under pressure from the pressurechamber 42, there is provided a release valve 45 carried by a movableabutment 46 operatively mounted in a chamber 41. The release valve 45 isurged toward an unseated position by a spring 4I, and when in unseatedposition establishes a communication between the chamber 42 and theatmosphere, by way of passages 48 and 49, chamber 41, and port 5.

The movable abutment 46 is subject on one side to pressure of fluid inthe chamber 42 and on the other side to pressure of a regulating spring5I. Tension on the regulating spring 5I may be regulated by anadjustable member 52 containing interiorly thereof a set screw 53providing a stop for a plunger 31 associated with the movable abutment46, to limit the travel thereof to the right.

For effecting unseating of the supply valve 43 and seating of therelease valve 45, there are Cil lio

provided spaced levers 54 pivotally carried at 55 intermediate theirends by a slidable pivot carrier B disposed in a bore 5l in the casing.

Secured between the upper ends of the spaced levers 54 is a member 58having associated therewith a stem 68 for engaging the supply valve 43.Rotatably held between the lower ends of the spaced levers 54 is aroller 8| adapted to engage stem 82 of release valve 45.

Carried by the member 58 and insulated therefrom by an insulatingelement 83 is a bridging contact 64, which is adapted to bridge andconnect together stationary application contacts 65 secured to andinsulated from the valve device casing. Carried by and insulated fromthe release valve stern 62 through an insulating member 68 is one memberof a pair of release contacts 61, the other member of which is carriedby and insulated from the movable abutment 48. As will be observed fromFig. 2,when the supply valve 43 is seated and the release valve 45 isunseated, conta'ots 65 are open and contacts t7 are closed.

When the slidable pivot carrier 58 is actuated to the right, the spacedlevers 54 iirst fulcrum about their upper ends to seat release valve 45,and when this valve is seated then fulcrum about their lower ends toeffect unseating oi supply valve 43. This sequence occurs because therelease valve spring 4| is a lighter spring than the supply valve spring44. During this operation the regulating spring 5|, which is heavierthan either or both of springs 4| and 44, is unappreciably compressed.It will thus be obvious that the amount supply valve 4-3 is unseateddepends upon the distance the slidable pivot carrier 56 is actuated tothe right.

For actuating the slidable pivot carrier 58 to the right, there isprovided a cam 88 secured to an operating shaft rotatable through ahandle 1|. The conguration of cam 89 is such that when handle 1| ismoved from a release position into an application Zone, pivot carrier 58is progressively moved to the right vario-us distances de pending uponthe degree of movement of handle 7|.

When the handle 7| is thus moved into the application zone and supplyvalve 43 unseated, uicl under pressure will iiow from main reservoir ilthrough main reservoir pipe 72, past unseated supply valve 43, topressure chamber 42, and from thence to straight air pipe i6. As thepressure in chamber 42 increases, the movable abutment 48 will be movedto the right, whereupon. spaced levers 54 will fulcrum about pivot 55 topermit r movement of supply valve 43 toward its seat under influence oiits spring 44. The parts are so designed that when a pressure in chamberi2 is reached corresponding to the degree or extent oi movement of thehandle 7|, movable abutment 46 will have moved far enough to the rightfor supply valve 43 to seat, thus lapping the supply to chamber 42.

If the pressure in chamber 42 should for any reason exceed thatcorresponding to the handle position, then movable abutment 46 will movefurther to the right to unseat release valve 45, and thus release fluidunder pressure to the atmosphere until the desired pressure isestablished. The pressure of uid thus supplied to and main tained inchamber 42 corresponds to the degree or extent of movement of handle 7|`When release valve is seated release contacts 61 will be opened, andwhen supply valve 43 is unseated application contacts 85 will be closed.The

purpose of these contacts will appear more fully later.

The magnet valve device 2|) is embodied in a casing provided with anapplication valve 74 and a release valve 75. urged toward seatedposition by a spring 78 and toward unseated position by action of anapplication electromagnet in the upper part of the valve device casing,which when energized actuates the valve downwardly. The release valve'l5 is also urged toward a seated position by a spring 77, and toward anunseated position by action of a release electromagnet, which whenenergized actuates this valve downwardly.

When the release valve 'l5 is unseated, a communcation is establishedbetween the straight air pipe iii and the atmosphere, by way of pipes78, 78 and 8E, past the unseated release valve 75, and through port 3|.When the release valve 'l5 is seated this communication is cut off, andwhen f the supply valve 74 is at the same time unseated, fluid underpressure may flow from the local reservoir i8 to the straight air pipeI8, by way embodied in a casing having as one of its essential elementsa rotatable drum 85 having secured thereto and insulated therefrom astepped Contact 88 adapted to engage stationary contacts iii carried byand insulated from the casing. The stationary contacts 87 are connectedto taps of a resistance 88, so that as the stepped 'contact 86successively engages and bridges the stationary contacts 87, segments ofthe resistance 88 will be shunted.

The rotatable drum 85 is secured to a shaft 89 which is suitablyjournaled in the casing and has secured thereto a pinion 88 adapted tomesh with arack 8| connected to a piston 92 disposed inf a pistonchamber 93. A spring 94 acts upon an abutment 85 secured to the rack 9|to bias the drum S5 and piston 82 to an off or release position.

When uid under pressure is supplied to charnber 83, piston 92 and rack9| are urged to the left until a balance is obtained between thepressure of iiuid in chamber 83 and the compression of spring 94. Drum85 is therefore rotated to a degree corresponding to the degree of Iiuidunder pressure supplied to chamber 88.

In order that the rotation of the drum 85 shall be controlled alsoaccording to the load on the vehicle as well as according to thepressure of fluid supplied to chamber 83, a mechanism is provided whichwill now be described. Slidably mounted on a shaft 88 is a crosshead 91which when moved to the right increases the tension on the spring 94. Alever 88 is pivotally mounted intermediate its ends'at 88 for actuatingthe crosshead 97 to the right. A rod |88 engages the lower end of leverS8 and is adapted to rotate the lever 88 to a degree depending upon thedeiiection of a sprung portion of the vehicle when loaded.

Attached to a sprung portion |83 of the vehicle is a bell crank leverlili having an arm |85 thereof adapted to engage a stop |532 secured tosome unsprung part 84 of the vehicle. When the vehicle is loaded thesprung part |83 Will move downwardly toward the unsprung part G4. If nowthe arm 585 is urged down into-engagement With stop |82, a link mitconnected to the bell crank lever lill will be actuated to the left toposition rod |00 accordingly.

vTo hold arm |05 in engagement with stop |92,

The application valve 74 is f of pipes 32 and 83, past the unseatedsupply valve .74, and pipes 8D, 78 and 78. rlhe eddy current brakecontrol device 22 is there is provided a piston |08 biased to the leftin a piston chamber |09 by spring |0'I and operatively connected withthe link |00 through a lever I I0 pivotally mounted intermediate itsends at |II to some part of the casing of the eddy current brake controldevice 22. Therefore, when fiuid under pressure is supplied to thechamber |09 rod 00 will be positioned to the left according to the loadon the vehicle.

For supplying iluid under pressure to the chamber |09, there is provideda magnet valve device |I2 having a supply valve ||3 and a. release valve|I4. A spring H5 urges the supply valve ||3 toward seated position andthe release valve ||4 toward unseated position. An electromagnet in theupper part of the valve device casing actuates the supply valve I|3 tounseated position and the release valve ||4 to seated position whenenergized, to effect a supply of fluid under pressure from the localsupply reservoir I8 to the chamber |09 by way of pipes 02 and 83, pastthe unseated supply valve IIS, and passage IIB. When the supply valveIIS is seated and the release valve I|4 unseated, this supply is cut 01Tand fluid under pressure supplied to the chamber |09 is released to theatmosphere by way of passage I I6, past the unseated release valve I I4,and port ||1.

It will thus be seen that when the magnet valve device is energized, atension will be placed on spring 94 according to the load on thevehicle, and when the magnet valve device is deenergized this tension isreleased. In order that the tension thus placed on spring 94 may beretained when the magnet valve device is deenergized, the rod |00 isprovided with a ratch |20 which is engaged by coacting serrated edges ofa pawl I2I, through action of a spring |22.

The spring |22 normally urges downwardly a piston |23, which isconnected with the pawl |2| through a stem |24. Piston |23 is disposedin a chamber |25 to which fluid under pressure is suppliedsimultaneously with that supplied to chamber |09. Therefore, when piston|08 in chamber |09 is actuated to the right piston |23 is actuatedupwardly to disengage pawl |2| from the ratch |20, thus permitting rod|00 to be positioned to the left.

When supply valve I I3 is seated and release valve I|4 unseated, torelease uid under pres-` sure from both chambers |00 and |25, spring |22actuates piston |23 downwardly to cause pawl I2I to again engage ratch|20 and thus hold rod |00 in the position to the left to which it Wasactuated by piston |00. The tension placed on spring 94 according to thevehicle load is thus retained after the magnet valve device has beendeenergized.

The pneumatic switch device 24 is embodied in a casing having a chamber|25 in which is disposed a piston I2'I actuated upwardly by a spring|28. The piston |2`| is provided with a stem |29 having secured theretoand insulated therefrom a contact |30 adapted to engage and connecttogether stationary contacts |35 when fluid under pressure is suppliedto chamber |26 to actuate piston |21 downwardly.

The suppression magnet valve device 26 is embodied in a casing providedwith a double beat valve |32, which is urged toward an upper seatedposition by a spring |33 and toward a lower seated position by action ofan electromagnet in the upper part of the valve device casing, whichwhen energized actuates the double beat valve downwardly.

When the double beat valve |32 is in upper seated position acommunication is established between the local supply reservoir I8 and achamber |34 of a double check valve device |35, by way of pipe |36, pastthe open lower seat of double beat valve |32, and pipe |31. When thedouble beat valve is in lower seated position, this communication is cutoff and a communication is established from the double check valvecharnber |34 to the atmosphere, past the open upper seat of double beatvalve |32, and port |38.

The transfer valve device 28 is embodied in a casing provided with aslide valve chamber |40 and a piston chamber I4I. Disposed in the slidevalve chamber |40 is a slide valve |42 and disposed in the pistonchamber I4! is a piston I 43 having a stem 44 recessed to receive theslide valve |42, so as to move it coextensive with movement of thepiston |43. A coil spring |45 engages the piston stem |44 and normallyacts to bias the piston |43 to its eXtreme left hand position. However,when fluid under pressure is supplied to the piston chamber |4| to adegree sufiicient to overbalance the combined pressure of fluid in slidevalve chamber |40 and that of spring |45, piston |43 will be actuated tothe right until it engages stops |46. Movement of piston |43 from itsextreme left hand to its extreme right hand position shifts slide valve|42 to control communications to be hereinafter more fully described.

The retardation detector device 30 is embodied in a casing comprising apendulum |50 pivotally mounted at |5| and adapted to control contacts|52. The contacts |52 are normally closed and are secured to thedetector device casing and insulated therefrom by insulating members|53. The pendulum |50 is provided with a nger |54 carrying an insulatingelement |55 adapted to engage one of the contacts |52 so as to open thecontacts when the pendulum is swung to the left.

The retardation detector device is positioned on the head end car sothat when the train is at rest or traveling at a constant rate of speedthe pendulum |50 remains in the vertical position shown in Figure 3,resting against stop |56. When, however, during deceleration of thetrain the rate of speed changes, the pendulum |50 swings to the leftunder the resulting force of inertia, and the finger |54 opens thecontacts |52 when the pendulum has swung through a predetermineddistance.

For opposing movement of the pendulum |50 to the left, there is provideda piston |53 disposed in a piston chamber |59 and provided with a stem|60 adapted to engage the pendulum. The opposition to movement of thependulum |50 by the piston |58 is proportional to the degree of fluidunder pressure supplied to the chamber |59, so that the rate ofdeceleration which will swing the pendulum to the left far enough toopen contacts |52 will depend upon the degree of pressure in the pistonchamber |59.

The reducing relay valve device 32 may be embodied in any convenientform of casing provided with a chamber IGI having a supply valve |62 forcontrolling the supply of fluid under pressure to the chamber and arelease valve |53 for controlling the release of iiuid under pressurefrom the chamber. The supply valve |02 and the release valve |33 arepreferably operated by a lever |64 pivoted intermediate its ends at E55to a lug |66 projecting from the valve device casing.

When no external force is acting upon the lever |64, a spring |61 holdsthe supply valve |52 seated, and a similar spring |66 holds the releasevalve |63 seated. When, however, lever |64 is rotated about its pivot|65 in a clockwise direction, supply valve |62 is unseated while releasevalve I 63 is urged against its seat with a greater force. When thelever |64 is rotated in the opposite or counterclockwise direction,release valve |63 is unseated and supply valve |62 Vis held seated withan increased force.

.For actuating the lever |64 there are provided two diaphragms |16 and|1l. The diaphragm |16 is subject on its upper side to pressure of fiuidin a chamber |12 and on its lower side to pressure of fluid in thechamber i6 I. The diaphragm |1| is subject on its upper side to pressureof fluid in a chamber |13, which chamber is maintained at atmosphericpressure by virtue of continuously open port |14 leading to theatmosphere, and is subject on its lower side to pressure of fluid in thechamber |6|.

The two diaphragms |10 and |1| are mechanically connected to the lever|64 through links or stems |15, and the arrangement is such that for agiven pressure of fluid supplied to chamber |12, the lever |64 will beactuated to hold supply valve |62 unseated until the pressure of fluidsupplied to chamber |6| bears a definite ratio to the pressure of uuidsupplied to chamber |12, whereupon diaphragms |16 and |1| move upwardlyfar enough to seat valve |62. For example, the two stems |15 may bespaced from the fulcrum point |65 so that the pressure established inthe chamber |6| will always be equal to one third of the pressure offluid supplied to the chamber |12.

If the pressure in chamber 16| should exceed this chosen ratio, thendiaphragms |16 and |1| would both be actuated upwardly far enough tounseat the release valve |63, and thus release fluid under pressure tothe atmosphere through exhaust passage |16 until the pressure haddropped to that corresponding to the selected ratio. It will thus beseen that the reducing relay valve device functions to establish inchamber |6| presi. sures bearing a xed ratio to pressures established inchamber |12.

The die-away magnet valve device 3! is preferably embodied in a casingprovided with a supply Valve |16 and an abutting release valve |19,urged toward seated and unseated positions, respectively, by a spring|65. An electromagnet in the upper part of the valve device casingfunctions when energized to unseat the supply valve |18 and seat therelease valve |16.

When the release valve |16 is seated, and the supply valve |18 unseated,a communication is established between a low pressure pipe I8! and asecond pipe |82, but when the supply Valve |16 is seated and the releasevalve |16 is unseated this communication is cut off and the pipe |82 isconnected to the atmosphere past the unseated release valve |16 andthrough exhaust port |83.

Each of the rectifier devices 34 comprises a bank of rectifier units |85connected as shown in i Fig. l, so that 'when input terminals |86 areconnected to the checking winding 33, output terminals |81 of onerectifier device are connected to the output terminals |61 of the otherrectifier device through a resistance device |66.

The individual rectier units |85 are connected to produce what is knownas full way rectification, and the two rectifier devices 34 areinter-connected so that the output voltage of one rectifier device addsto the output voltage of the other rectifier device, the voltage dropacross the resistance device |88 then being proportional to the combinedoutput voltages of the two rectier devices.

The checking winding 33 of each eddy current brake device may beincorporated in the eddy current brake device in the manner shown in myaforesaid patent, and is preferably arranged so that the voltageproduced therein is proportional to the braking eifect produced by theeddy current brake device. It is to be here understood that each twoeddy current brake devices will have associated therewith two rectierdevices 34 connected to the associated checking windings 33 as indicatedin Fig. 1. I

rThe wheel siip detector relay 35 is preferably connected between thetwo common output terminals |81' of the two rectifier devices 34 and themid-point of the resistance device |88, so that with the output voltagesof the two rectifier devices equal the wheel slip detector relay will bedeenergized. When, however, the output voltage of one rectifier devicedrops substantially below the output Voltage of the other rectifierdevice, as when the wheels braked by one eddy current brake begin toslip, the wheel slip detector relay will be energized. This relay ispreferably of the slow release type, so that when the slipping wheelsagain rotate at normal speed a predetermined interval of time elapsesupon deenergization of the relay before it will open its contacts.

The motion detector device 39 preferably includes a casing formed fromelectrically insulating materials having disposed therein in spacedrelationship two electrically conducting plates |66, between which aredisposed granules of some conducting material |9|, as for example carbongranules. The motion detector device is preferably secured to some partof the head end car which is subject to appreciable vibration while thecar is in motion.

The feature of importance in connection with the motion detector device36 is that while the vehicle is in motion above a certainpredeterminedspeed, as for example seven or eight miles per hour, themotion detector device will be vibrated sufficiently so that theconducting path between the two plates |96, through the granules |9l,will be of such resistance that the motion detector relay 33 connectedin circuit therewith will be insufficiently energized to actuate itscontacts. When, however, the speed of the vehicle drops below seven oreight miles per hour, the

granules ist will settle and diminish the resistance to a value suchthat the motion detector relay 36 will be energized sufficiently toclose its contacts. From experience it has been determined that duringappreciable vibration the resistance between the plates |96 may arise toas much as ten times the resistance when at rest.

The push switch 46 comprises essentially a bridging contact |92 normallybiased by a spring |93 to a position where it bridges stationarycontacts |94. When a push button |95 is depressed, contact |62 isdisengaged from contacts |64.

While the push switch 46 has been shown as being of the manuallyoperated type, it is to be understood that this type is merelyillustrative of one of a large number of types which may be employed toperform a similar function.

The operation of this embodiment of my inventionis as follows:

Running condition When the train is running under power or coasting,handle II of the brake valve device I5 is maintained in releaseposition, and, as will appear more fully hereinafter, both the eddycurrent brakes and fluid pressure brakes will be held released.

During running condition the main reservoir I'I on the head end car, andthe main reservoir pipe 'I2 which extends throughout the'train, aremaintained charged from the usual compressor equipment (not shown) tosome predetermined value, as for example from ninety to one hundred andve pounds per square inch. Each local supply reservoir I8 on each car inthe train will then be charged from the main reservoir pipe 'l2 througha non-return check valve device |96, which permits flow from the mainreservoir pipe to the local supply reservoir but prevents flow in thereverse direction, so that if the main reservoir pipe is rupturedsufficient fiuid under pressure will be retained in the local supplyreservoir to insure an application of the brakes on each car.

The suppression magnet valve device 26 on each car will be deenergizedduring running condition, so that fluid under pressure at local supplyreservoir pressure will be supplied to piston chamber I4I of thetransfer valve device 28. The piston |43 and slide valve |42 of each ofthese devices will be thus positioned as shown in Fig. 7.

Motion detector relay 38 will be deenergized during running condition solong as the speed of the vehicle is above some low chosen value, as forexample the seven or eight miles per hour heretofore assumed.

Before the train is started up, the motion detector relay 38 will beenergized from a battery I9`| on the head end car through a circuitwhich includes conductor |98, battery train wire |99, conductors 200 and20|, relay 38, conductor 202, and motion detector device 39, the returncircuit to the battery |97 being by Way of ground connection 203. Relay38 will then open its upper contacts 204 and close its lower contacts205.

Closing of the lower contacts 205 energizes the magnet valve device I I2in each eddy current brake control device 22, through a circuit whichbeginning at the battery train wire |99 includes conductor 200, pushswitch device 40, conductor 206, contacts 205 of relay 38, trainconductor 201, and branch conductor 208, the return circuit to thebattery being through ground connection 209. The magnet valve device II2being thus energized will seat its release valve II4 and unseat itssupply valve II3, to effect a supply of fluid under pressure to bothpiston chambers |09 and |25. As before explained, a tension will then beplaced on spring 94 according to the load on the car with which the eddycurrent brake control device 22 is associated. Each eddy current brakecontrol device 22 will therefore be pre-conditioned to produce an eddycurrent braking effect on each car corresponding to the load on thatindividual car.

While the vehicle is running and the motion detector relay 33 isdeenergized, or insufficiently energized to maintain its contacts 205closed, the magnet valve device I|2 in each eddy current brake controldevice 22 will be deenergized. Ihe load control portion of each eddycurrent brake control device 22 is therefore operative only while thetrain is at rest or below the speed which operates the motion detectorrelay 38.

The other parts of the brake equipment not specifically referred to willbe in the positions shown in the drawings, during running condition.

Service application When it is desired to effect a service applicationof the brakes, the brake valve handle 1I is moved into the applicationzone to a degree according to the desired degree of braking. Releasevalve 45 is then seated and supply valve 43 unseated, to effect a supplyof fluid under pressure from the main reservoir I'I to the pressurechamber 42 to-a degree corresponding to the extent of movement of handleI, as heretofore explained.

At the same time, seating of release valve 45l opens release contactsIS'I, while unseating of supply Valve 43 closes application contacts 65.Opening of release contacts Sl effects deenergization of the releaseelectromagnet in the magnet valve device 20 on each car in the train, byinterrupting a circuit from battery train wire |99, which includesconductor 2| I, release contacts 6l, release train conductor 2I2, branchconductor 2I3, the release electromagnet, and ground connection 2M.Release valve l5 is then seated by spring VI to close the local exhaustcommunication between the straight air pipe I6 and the atmosphere.

Closing of application contacts 65 effects energization of theapplication electromagnet in each magnet Valve device 20, byestablishing a circuit from the battery train wire |99 which includesconductors 200 and 2I5, application contacts 65, application trainconductor 2 I6, branch conductor 2H, the application electromagnet, andground connection 2I4. The supply valve 14 in each magnet valve device20 is then unseated, to supply fluid under pressure locally from eachsupply reservoir I8 to the straight air pipe I6, through the pipes andpassages heretofore described. Straight air pipe pressure will then bequickly established throughout the train.

When the pressure in the pressure chamber 42 of the brake valve deviceI5 reaches that corresponding to the position of handle "II, movableabutment 40 will effect seating of supply valve 43 and opening ofapplication contacts 05, while maintaining release valve 45 seated andrelease contacts 61 opened. Straight air pipe pressure throughout thetrain will then correspond to the position of handle 1I.

Fluid under pressure in the straight air pipe I6 flows to piston chamber93 in each eddy current brake control device 22, by way of branch pipes'i8 and 79. With spring 94 in each control device 22 conditionedaccording to the load on that car, drum will be rotated until a balanceis obtained between the pressure exerted by spring 94 and the pressureof uid in chamber 93. Sections of resistance 88 will therefore beshunted, so that the current supplied to the eddy current brake windingsI0 will cause the eddy current brake devices to produce a braking effectproportional to both straight air pipe pressure and the car load.

Current to energize the eddy current brake windings may be supplied froma power plant on the train, from a third rail, or through a trolley 2I8.In the embodiment shown, the circuit from the trolley 2I8 is controlledby the aforementioned line switch or contactor 23. Energization of thisline contactor is controlled by the motion detector relay 38 andpneumatic switch device 24. At a low pressure of fluid in the straightair pipe I6, as for example five pounds per square inch, pneumaticswitch device 24 actuates its movable Contact |30 into engagement withsta- Cri tionary contacts I 3|, and since during running conditioncontacts 204 of motion detector relay 38 will be closed, line contacter23 will be energized through a circuit which beginning at battery trainwire |99 includes, conductor 200, push switch device lili, conductor266, contacts i3d and ISI of pneumatic switch device 24E, contacts 204of motion detector relay 38, train wire 220, line contactor 23, andground connection 22| Line contactor 23 will then close its contacts tocomplete the circuit to the eddy current brake windings il), whichcircuit includes trolley 2|8, contacts of line contacter 23, all or aportion of resistance 88, conductor 222, contact 223 of selector relay36, conductor 224, resistance device 225, conductor 226, eddy currentbrake windings it and ground connection 221. The eddy current brakedevices will thus be applied to a degree corresponding to the positionof handle il and to the load on the individual car.

Fluid under pressure in the straight air pipe it also flows by way ofbranch pipe 'it to chamber |12 in each reducing relay valve device 32.Diaphragm |10 is then actuated downwardly to effect unseating of supplyvalve |62, to supply fluid under pressure from the local supplyreservoir i8 to chamber IGI, by way of pipe and passage 228. yAs soon asthe pressure of uid in chamber iti has reached a value bearing a denniteratio to the pressure of fluid in the straight air pipe, diaphragms |73and |'I| will be actuated upwardly far enough to effect Seating ofsupply valve |62. For the purpose of illustration, it will be assumedthat the pressure established in chamber it! will y be one third of thepressure in chamber |12 and the straight air pipe iii.

From chamber i6! fluid ows through low pressure pipe |8| to the die-awaymagnet valve device 3| and through pipe 235 to the transfer valve device28.

Now since the eddy current brakes are immediately effective at the highspeeds, the train will be decelerated at a rate corresponding to thedegree of application of the eddy current brakes. The resulting inertiaeffect on the pendulum |53 of the retardation detector device 30 willcanse the pendulum to swing to the left. Before the pendulum swings tothe left contacts |52 will be closed and thus cause die-away magnetvalve device 3| to be energized through a circuit which includes frombattery train wire |93, conductor B, push switch device 4S, conductor26S, contacts |353 and |3| of pneumatic switch device 24, conductor D,contacts |52, train conductor 25i,

. branch conductor 252, magnet valve device 3|,

and ground connection 235. As the pendulum swings to the left thiscircuit is interrupted and the die-away magnet Valve device 3| isdeenergized. When this magnet valve device is deenergized, supply valve|18 is seated and communication between low pressure pipe itl and pipe|82 is cut off.

Movement of pendulum |50 to the left is opposed by fluid pressure actingon piston |53, due

i to the flow of fluid from the straight air pipe i However, for anyv tothe piston chamber |59. given degree of application of the eddy currentbrakes, the pendulum |59 will be swung far enough to the left to opencontacts |52. The die-away magnet valve device 3| will thus be caused toprevent an application of the iiuid presvalve device 28 ilows to slidevalve chamber |40.' Up to this time piston |43 has been subject to fluidpressure from piston chamber lili only, and has thus been actuated toits right hand position, as shown in Fig. '7.

Now if the piston M3 and slide valve |42 of the transfer valve device 2Swere to remain in the positions shown in Fig. 7, then fluid underpressure in the straight air pipe i5 would also flow to the brakecylinders I2 through branch pipes 18, 'iQ and 23d, cavity 23| in slidevalve |42, and brake cylinder pipe 232. However, when current issupplied to the eddy current brake windings l@ through the resistancedevice 225, the power responsive relay 25, which is shunted acrossresistance device will be energized at a .low value ci power current andthus closeits contacts.

With these contacts closed, the suppression magnet valve device 25 isenergized from the train battery wire til?, through a circuit whichincludes conductor |98, contacts of relay 25, conductor 231i, magnetvalve device 25, and ground connection 235. The suppression magnet valvedevice 2B then actuates its double beat valve |32 to lower seatedposition, to disconnect transfer valve piston chamber MI from the localsupply reservoir i8, and to vent this chamber to the atmosphere, throughexhaust port 33 in the suppression magnet valve device.

Fluid under pressure will then new from piston chamber ifll throughchamber |34 of double check valve device |35, and pipe |31' to theatmosphere. The opposite chamber Edil of the double check valve device|35 is connected to the straight air pipe i6 by way of branch pipe it,so that as soon as the pressure in chamber i3d has dropped slightlybelow the pressure in the straight air pipe, slide valve 24| in thedouble check valve device will be shifted to the left, and the pressureof fluid in the transfer valve piston chamber Il will remain at straightair pipe value.

Now spring M5 in the transfer valve device is designed to actuate pistonIlli to its left hand position whenever the differential fluid pressureacting to the left of the piston diminishes below a predetermined value,as for example fty pounds per square inch. That is, whenever the viiuidpressure in piston chamber ifii does not exceed the fluid pressure inslide valve chamber Ifl by more than nity pounds per square inch, springit actuates thepiston and slide valve to the left.

For the conditions assumed in the present case, the maximum straight airpipe pressure which may be effected during a service application willnot exceed sixty-five pounds per square inch. Therefore, since thepressure in the low pressure pipe 53| will be one third of the straightair pipe pressure, it will be obvious that the fluid pressurediiferential acting to the left of the piston will be considerably belowfifty pounds per square inch during a service application. Spring |55will therefore shift piston M3 and slide valve M2 to their extreme lefthand positions, so that fluid does not iiow from the straight air pipel@ to the brake cylinders i2.

It will thus be seen that during a service application of the brakes theeddy current brakes only are applied while the fluid pressure brakes areconditioned as a stand-by brake.

Since the braking effect produced by the eddy current brake devices willproduce a substantially constant rate of retardation, the train will bedecelerated smoothly. If, however, the v train should run onto aslippery rail, and it be assumed that the wheels brake by `one of theeddy current brake devices should begin to slip, then the voltageproduced by the checking winding 33 associated with that brake devicewould diminish, and as a consequence wheel slip detector relay 35 wouldbe energized. When this relay is energized it closes both its uppercontacts 243 and its lower contacts 244. Closing of the upper contacts243 provides a by-pass circuit around the contacts of the power responserelay 25, so as to insure energization of the suppression magnet valvedevice 26 when the current supplied to the eddy current brake windingsis subsequently cut off.

Closing of lower contacts 244 energizes the selector relay 36, through acircuit which beginning at train battery wire |99 includes conductor|93,

contacts 244, selector relay 36 and ground connection 245. The selectorrelay 36 then opens its lcwer contact 223 and closes its upper contact246. Opening of lower contact 223 cuts oir the supply of current to theeddy brake windings |0, while closing of upper contact 246 connects aresistance device 241 in circuit with the resistance 88 of the eddycurrent brake control device 22.

The resistance device 241 has a resistance value substantially equal totwo eddy current brake windings |0, so that if there are a number ofsuch pairs of eddy current brake windings on the car, then thedisconnection of 'any two such sets will not materially raise thevoltage on the remaining sets and thereby cause them to produce anincreased braking eiect, such as would possibly cause additional wheelsto slide.

With the brakes associated with the slipping wheels thus whollyreleased, the slipping wheels will again pick up speed and will in allprobability again roll at normal speed. The unbalanced low voltagecondition resulting during slipping wheel condition will thereforegradually change to a balanced voltage condition, and wheel slipdetector relay 35 will after a predetermined interval of time open itscontacts 243 and 244. Selector relay 36 will then be deenergized toagain close the circuit to the eddy current brake windings l, and powerresponse relay 25 will also be energized to maintain suppression magnetvalve device 26 energized.

This cycle will repeat itself until the rail conditions improve to thepoint where wheel slipping does not occur.

If the current supply to the eddy current brake windings I should fail,then power response relay 25 would be deenergized and suppression magnetvalve device 26 would as a consequence also be deenergized. Fluid underpressure would then ilow from the local supply reservoir I8 totransiervalve piston chamber |4|, and since the pressure of this supply is from90 to "105 pounds per square inch, a pressure differential on piston |43would be produced great enough to shift slide valve |42 to the extremeright hand position.

Cavity 23| will then connect pipes 230 and 232, so that iluid underpressure would flow from the straight air pipe I6 to the brake cylinders|2, and thus produce a brake application to a degree correspondingdirectly to straight air pipe pressure.

Now when the train speed diminishes to approximately ten miles per hourdue to eddy current braking, the braking effect produced by the eddycurrent brake devices will diminish, rst slowly and then rapidly, and asa consequence the rate of retardation will reduce. When the rate ofretardation has reduced to approximately one half of that produced atthe upper speeds by an application of the eddy current brakes, thependulum |50 will have receded toward its neutral position far enoughfor contacts |52 to close. Closing of these cont-acts again completesthe circuit to the die-away magnet valve device 3|, and this magnetvalve device seats its release valve H9 and unseats its supply valve|18.

Fluid under pressure then flows from the low pressure pipe |8|, past theunseated supply valve |18, through pipe |32, cavity 23| of slide valve|42 in transfer valve device 28, and brake cylinder pipe 232 to thebrake cylinders I2. The iluid pressure brakes will thus be applied asthe eddy current brakes are diminishing in effectiveness.

Now since the pressure of fluid in the low pressure pipe |8| is only onethird of that in the straight air pipe |6, the fluid pressure brakeswill be applied to a much lower degree than were the eddy current brakesinitially, so that the train will be brought to a smooth stop free ofshock.

At a speed of about seven or eight miles per hour, the motion detectorrelay 38 will be sufriciently energized to open its contacts 204 and toclose its contacts 205. Opening of contacts 204 causes deenergization ofline contactor 23, thereby deenergizing the eddy current brake windingsi0 and thus effecting a release of the eddy current brakes. Closing ofcontacts 205 renders efective the load control portion of the eddycurrent brake control valve device 22, as previously described.

Therefore, as the train comes to a stop the eddy current brake deviceswill be cut out of action and the fluid pressure brakes will be applied.To eiect a release of the brakes, the brake valve handle is turned torelease position, whereupon the straight air pipe |6 is vented to theatmosphere at the head end of the train through the brake valve deviceI5, and locally on each car past the unseated release valve 'I5 in eachmagnet valve device 20. Tne parts then assume the release positionsshown in the drawings.

Emergency application When it is desired to effect an emergencyapplication of the brakes, the brake valve handle is turned to theextreme application position, where supply valve 43 of the brake valvedevice is held unseated sufliciently to permit main reservoir pressureto be established in the pressure chamber 42, and where applicationcontacts 65 are maintained closed. The straight air pipe therefore willbe supplied with fluid at main reservoir pressure, with the result thatthe eddy current brakes will be applied to a maximum degree. In allother respects an emergency application of the brakes is the same as aservice application, the diierence being one of degree rather than infunction.

To effect a release of the brakes following an emergency application,the brake valve handle is turned to release position, and the brakesthus released as for a release following a service application.

Now if at any time it is desired to render the eddy current brakesinoperative, pressure is manually applied to the push button |95 of thepush switch device 40. This effects disengagement of contacts |92 fromcontacts |94, and prevents energization of line contacter 23.Application of thebrakes may then be effected only by operation of thefluid pressure brakes, which, as will be obvious from the precedingdescription, will be to a degree corresponding directly to straight airpipe pressure as the suppression magnet valve device 26 will bedeenergized, the piston |43 of transfer valve device 28 thus positionedto the right, and straight air pipe I 6 therefore connected to brakecylinder pipe 232 by cavity 23| in slide valve |42.

While I have illustrated my invention in connection with a singleembodiment thereof, it will be apparent to those skilled in the art thatmany' modications and changes therein may be made and I do not wish tobe limited in this respect 10 other than by the spirit and scope 'of theap= pended claims. i

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is: Y

1. In a train brake system, in combination, fluid pressure brake meansand electric brake means associated with each car in the train, a pipeadapted to extend throughout the train, control means on the head endcar havingl a manually operated element for controlling the supply offluid under pressure to and its release from said pipe on the head endcar according to the degree of movement of said element,electroresponsiveV valve means on one ci' more cars throughout the trainfor controlling the supply of nuid under pressure to and its releasefrom said pipe in synchronism with s aid control means and alsoaccording to the degree of movement of said element, and means forcontrolling applications of said fluid pressure brake means and saidelectric brake means according to the pressure of nuid in said pipe.

2. In a vehicle brake system, in combination, iiuid pressure brakemeans, electric brake means, means for effecting an application of saidelectric brake means, and means operable when the degree of eectivenessof said electric brake means diminishes below a predetermined value foref'- fecting an application of said uid pressure brake means to a degreehaving a fixed ratio to the initial degree of application of saidelectric brake means.

3. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means operable to produce a braking effect whichdiminishes at low rotational speeds, a pipe, means for establishingfluid pressures in said pipe,` means for .effecting an application ofsaid electric brake means according to the degree of pressure in saidpipe, and means operable when the degree of braking effect produced bysaid electric brake means diminishes below a predetermined value foreffecting an application of said fluid pressure brake means to a degreecorresponding to a fraction of the pressure established in said pipe.

4. In a vehicle brake system, in combination fluid pressure brake means,electric brake means, a pipe, means for establishing iiuid pressures insaid pipe according to a desired degree of application of the brakes,means for effecting an application of said electric brake meansaccordingvto pressures established in said pipe, means operable when theeffectiveness of the electric brake means diminishes below apredetermined degree for eiecting an application of said fluid pressurebrake means, and means for limiting the effectiveness of the fluidpressure brake means to a degree corresponding to a pressure less thanthat established in said pipe,

5. In a Vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for establishinguid pressuresin said pipe according to desired degrees of braking, means foreffecting an application of said electric means for effecting anapplication of said electric brake means according to pressuresestablished in said pipe, means also operable to effect an applicationof said fluid pressure brake means also according to pressuresestablished in said pipe but to a degree less than and bearing a fixedratio to the degree of application of said electric brake means, andmeans preventing said application of iiuid pressure brake meansuntil thedegree of effectiveness of the electric brake means diminishes to apredetermined value.

7. In a vehicle brake system, in combination, huid pressure brake means,electric brake means, a pipe, means for establishing a fluid pressure insaid pipe according to a desired degree of braking, means for effectingan application of said electric brakemeans according to the degree ofpressure established in said pipe, means responsive to the pressure insaid pipe and having a chamber in which a fluid pressure is establishedto a degree less than that established in said pipe, and means operablewhen the effectiveness of said electric brake means diminishes below apredetermined value for effecting an application cf said fluid pressurebrake means according to the pressure established in said chamber.

8. In a vehicle brake system, in combination, a brake cylinder, anelectric brake device operable to produce a braking effect whichdiminishes at low rotational speeds, a pipe, means for establishingfluid pressures in said pipe, means for effecting an application of saidelectric brake device according to pressures established in said pipe, avalve device having a chamber and operable to establish pressures insaid chamber less than and bearing a fixed ratio to the pressures insaid pipe, and means operable when the braking effect produced by saidelectric brake device diminishes below a predetermined value foreffecting a supply of fluid under pressure to said brake cylinder to adegree corresponding to the degree of pressure in said chamber.

9. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe adapted to have iiuid under pressuresupplied thereto, a reducing relay valve device operably responsive topressure of fluid in said pipe to supply fluid under pressure to areduced degree to effect an application of said fluid pressure brakemeans, and means operable when effecting an application of said electricbrake means for preventing said application of said fluid pressure brakemeans until the degree of effectiveness of said electric brake means hasdiminished below a predetermined degree.

10. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe adapted to have iluid under pressuresupplied thereto, means for effecting an application of said electricbrake means according to the degree of fluid under pressure supplied tosaid pipe, a valve device responsive to the pressure of fluid in saidpipe for effecting a supply of fluid under pressure to said fluidpressure brake means' to a degree less than and bearing a xed ratio tothe pressure of fluid in said pipe, electroresponsive valve means forcontrolling said reduced supply, and means controlled by the electricbrake means for controlling said electroresponsive valve means.

11. In a. vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for supplying fluid underpressure to said pipe to a degree according to a desired degree ofbraking, means for effecting an application of said electric brake meansin response and according to the degree of fluid under pressure suppliedto said pipe, means also responsive to fluid under pressure supplied tosaid pipe for effecting an application of said fluid pressure brakemeans, and means governed by the rate of retardation of the vehicle forpreventing said application of said fluid pressure brake means until thedegree of effectiveness of the electric brake means has diminished to apredetermined value.

12. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, means for effecting an application of saidelectric brake means, means operated according to the rate ofretardation of the vehicle, means responsive to operation of said lastmeans above a selected rate of retardation for preventing an applicationof said fluid pressure brake means and operable below said selected rateof retardation for effecting an application of said fluid pressure brakemeans, and means for establishing said selected rate of retardationaccording to the degree of application of said electric brake means.

13. In a vehicle brake system, in combination, a fluid pressure brakemeans, an electric brake means, a pipe, means for supplying fluid underpressure to said pipe, means for effecting an application of saidelectric brake means according to the pressure of fluid supplied to saidpipe, means governed by the rate of retardation of the vehicle fordelaying effective application of said fluid pressure brake means, andmeans for controlling said last means according to the pressure of fluidsupplied to said pipe.

14. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for supplying fluid underpressure to said pipe, means for effecting an application of saidelectric brake means according to the pressure of fluid supplied to saidpipe, means operated according to the rate of retardation of thevehicle, means responsive to a chosen operation of said last means forpreventing an application of said fluid pressure brake means, andresponsive to a different operation of said last means for effecting anapplication of said fluid pressure brake means, and means responsive tothe pressure of fluid supplied to said pipe for controlling saidretardation controlled means.

15. In a vehicle brake system, in combination, a fluid pressure brakemeans, an electric brake means, means for effecting an application ofsaid electric brake means, a set of contacts, means including a pendulumdevice responsive to the rate of retardation of the vehicle foroperating said contacts, means responsive to one operation of saidcontacts for preventing an application of said fluid pressure brakemeans and responsive to another operation of said contacts for effectingan application of said fluid pressure brake means.

16. In a vehicle brake system, in combination, a fluid pressure brakemeans, an electric brake means, means for effecting an application ofsaid electric brake means, normally closed contacts, means operable whensaid contacts are closed for effecting an application of said fluidpressure brake means, and means including a pendulum device governed bythe rate of retardation of the vehicle for maintaining said contactsopen above a predetermined rate of retardation and for closing saidcontacts below said rate.

1'7. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for supplying fluid underpressure to said pipe, means for effecting an application of saidelectric brake means according to the pressure of fluid supplied to saidpipe, .a set of contacts, means responsive to operation of said contactsfor effecting an application of said fluid pressure brake means, inertiaoperated means operated according to the rate of retardation of thevehicle for operating said contacts to prevent application of said fluidpressure brake means, and means operated according to the pressure offluid in said pipe for controlling operation of said inertia operatedmeans.

18. In a vehicle brake system, in combination, a fluid pressure brakemeans, an electric brake means, a pipe, means for supplying fluid underpressure to said pipe, means for effecting an application of saidelectric brake means according to the pressure of fluid supplied to saidpipe, means operable to effect an application of said fluid pressurebrake means either to a degree according to the degree of pressure insaid pipe or to a degree less than according to the pressure in saidpipe, means operable upon total failure of said electric brake means tocause said last means to effect an application of said fluid pressurebrake means according to the degree of pressure in said pipe butoperable upon a predetermined decrease in effectiveness only of saidelectric brake means for causing said last means to effect anapplication of said fluid pressure brake means to said lesser degree.

19. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for effecting an applicationof said electric brake means according to the degree of fluid underpressure supplied to said pipe, means operable While the electric brakemeans is effective in producing a desired braking effect for preventingapplication of said fluid pressure brake means, means operable when theelectric braking effect diminishes below a predetermined value foreffecting an application of said fluid pressure brake means to a degreeless than and bearing a xed ratio to the degree of pressure in saidpipe, and means for delaying application of said fluid pressure brakemeans for a definite interval of time.

20. In a vehicle brake system, in combination, electric brake means, apipe, means for supplying fluid under pressure to said pipe, means foreffecting an application of said electric brake means according to thepressure of fluid supplied to said pipe, and means operable so long asthe pressure in said pipe is above a predetermined value for cuttingsaid electric brake means out of action when the speed of the vehiclediminishes below a chosen value.

21. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for supplying fluid underpressure to said pipe, means for effecting an application of saidelectricbrake means according to the pressure of fluid supplied to saidpipe, means operative while said electric brake means is effective forpreventing an application of said fluid pressure means and operativewhen said electric brake means is cut out of action for effecting anapplication of said fluid pressure brake means according to the pressureof fluid supplied to said pipe, and manually controlled means forcutting said electric brake means out of action at Will.

22. In a Vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, means for effecting an application of saidelectric brake means, a valve device operable in a first position toeffect an application of said fluid pressure brake means to one degreeand operable in a second position to effect .an application to adifferent degree, and means for maintaining said Valve device in saidfirst position so long as said electric brake means is effective and forshifting said valve device to said second position upon failure of saidelectric brake means.

23. In a vehicle brake system, in combination, a brake cylinder, a firstpipe adapted to have fluid under pressure supplied thereto to onedegree, a second pipe adapted to have fluid under pressure suppliedthereto to a lower degree, a valve device operable in one position tosupply fluid under pressure from said first pipe to said brake cylinderand being shiftable to a second position to supply fluid under pressurefrom said second pipe to said brake cylinder, electric brake means,means operable upon effecting an application of said electric brakemeans for shifting said Valve device to said second position andoperable upon failure of said electric brake means for shifting saidvalve device to said first position.

24. In a vehicle brake system, in combination,

electric brake means, a circuit for supplying current to operate saidelectric brake means, means for connecting said circuit to a source ofcurrent supply, the E. M. F. of said source diminishing when soconnected due to the current load, means for disconnecting said circuitfrom said source during the time Wheels braked by said brake means areslipping, and means for preventing the E. M. F. of said source fromincreasing due to decrease in current load while said Wheels areslipping.

25. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a control pipe through which fluid underpressure is supplied to effect an application of the brakes, means forcontrolling the operation of said electric brake means to produce abraking effect thereby corresponding directly to the pressure of fluidin said control pipe, an application pipe through which fluid underpressure is supplied to effect the operation of said fluid pressurebrake means to produce a braking effect thereby corresponding to thepressure in said application pipe, and valve means interconnecting saidcontrol pipe and said application pipe and operable in response topressures in said control pipe to establish fluid pressures in saidapplication pipe to a degree bearing a xed ratio to the degree ofpressure in said control pipe.

26. In a vehicle brake system,.in combination, fluid pressure brakemeans, electric brake means, a pipe through which fluid under pressureis supplied to effect an application of the brakes, means responsive topressure in said pipe for effecting the operation of said electric brakemeans to produce a braking effect corresponding directly to the degreeof pressure in said pipe, and means responsive also to pressure in saidpipe for effecting a supply of fluid under pressure to a degree lessthan and. bearing a fixed ratio to the pressure in said pipe, to effectthe operation of said fluid pressure brake means.

27. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for establishing fluidpressures in said pipe, means for controlling the operation of saidelectric brake means to cause a braking effect to be produced therebycorresponding to the pressure established in said pipe, and valve meansconnected to and interposed between said pipe and said fluid pressurebrake means for establishing fluid pressures to a degree less than butgoverned by the degree of pressure in said pipe, to control theoperation of said fluid pressure brake means.

28. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a control pipe through which fluid underpressure is supplied to effect an application of the brakes, means forcontrolling the operation of said electric brake means to produce abraking effect thereby corresponding directly to the pressure of fluidin said pipe, means including an application pipe through which uidunder pressure is supplied to effect the operation of said fluidpressure brake means to produce a braking effect thereby correspondingto the pressure in said application pipe, Valve means interconnectingsaid control pipe and said application pipe and operable in response topressures in said control pipe to establish fluid pressures in saidapplication pipe to a degree bearing a fixed ratio to the degree ofpressure in said control pipe, a positionable element, and means foralso controlling the operation of said fluid pressure brake meansaccording tothe position of said element.

29. In a Vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe through which fluid under pressureis supplied to effect an application of the brakes, means responsive topressures in said pipe for effecting the operation of said electricbrake means to produce a braking effect corresponding directly to thedegree of pressure in said pipe, means responsive also to pressure insaid pipe for effecting a supply of fluid under pressure to a degreeless than and bearing a fixed ratio to the pressure in said pipe, toeffect the operation of said fluid pressure brake means, a positionableelement, and means for also controlling the operation of said fluidpressure brake means according to the position of said element.

30. In a vehicle brake system, in combination, fluid pressure brakemeans, electric brake means, a pipe, means for establishing fluidpressures in said pipe, means for controlling the operation of saidelectric brake means to cause a braking effect to be produced therebycorresponding to the pressures established in said pipe, Valve meansconnected to said pipe and interposed between said pipe and said fluidpressure brake means for establishing fluid pressures t a degree lessthan but governed by the degree of pressure in said pipe, to control theoperation of said fluid pressure brake means, a positionable element,and means for also controlling the operation of said fluid pressurebrake means according to the position of said element.

JOHN W. LOGAN, JR.

CTL

